TWI849359B - Polyimide film, method of producing the same, flexible metal foil laminate and electronic component containing the same - Google Patents

Abstract

The present invention provides a polyimide film and a method for manufacturing the same. The polyimide film satisfies the following formula (1) in the dimensional change measurement based on a thermomechanical analyzer (TMA) after a heating process from 25°C to 400°C and a cooling process from 400°C to 25°C. Formula (1) TD direction dimensional measurement value (cooling, 50°C) - TD direction dimensional measurement value (heating, 50°C) < 0 μm

Description

Polyimide film, method for producing the same, flexible metal foil laminate and electronic component containing the same

The present invention relates to a polyimide film that maintains flatness and does not produce wrinkles even after metal foil coating, sputtering or deposition, and a method for manufacturing the same.

Polyimide (PI) is a polymer material based on a rigid aromatic main chain and an imide ring with excellent chemical stability. It also has the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials.

Polyimide films have attracted much attention as materials for various electronic devices that require the above-mentioned properties.

Microelectronic components using polyimide films can be, for example, flexible ultra-thin circuit substrates with high circuit integration, so as to cope with the lightweight and miniaturization of electronic products. Polyimide films are particularly widely used as insulating films for thin circuit substrates.

The structure of the aforementioned ultra-thin circuit substrate is generally a circuit including a metal foil formed on an insulating film. In a broad sense, this ultra-thin circuit substrate is called a flexible metal foil clad laminate (Flexible Metal Foil Clad Laminate). When a thin copper plate is used as the metal foil, in a narrow sense, it is also called a flexible copper clad laminate (Flexible Copper Clad Laminate; FCCL).

As a method for manufacturing a flexible metal-clad laminate, for example: (i) a casting method in which polyamide, which is a precursor of polyimide, is cast or coated on a metal foil and then imidized; (ii) a metallization method in which a metal layer is directly provided on a polyimide film by sputtering; and (iii) a lamination method in which a polyimide film is bonded to a metal foil by heat and pressure using thermoplastic polyimide.

In particular, the metallization method, such as sputtering copper or other metals on a polyimide film with a thickness of 20μm to 38μm and depositing a bonding layer and a seed layer in sequence, to produce a flexible metal-clad laminate, has advantages in forming ultra-fine circuits with a peak (pitch) of circuit patterns below 35μm, and is widely used to manufacture flexible metal-clad laminates for chip on film (COF).

Recently, polyimide films used in flexible metal foil laminates manufactured by metallization methods have been experiencing a problem of reduced flatness and wrinkles after metal foil lamination.

Therefore, there is an urgent need for a polyimide film that maintains flatness even after metal foil lamination.

The matters described in the above prior art are used to help understand the background of the invention and may include matters of the prior art that are not known to ordinary technicians in the technical field.

[Prior Art Literature]

[Patent Literature]

Patent document 1: Korean patent number 10-1375276.

Patent document 2: Korean Publication Patent Gazette No. 2016-0002402.

Therefore, the object of the present invention is to provide a polyimide film that maintains flatness and does not wrinkle after metal foil coating, sputtering or deposition.

However, the issues to be solved by the present invention are not limited to the issues mentioned above, and practitioners can clearly understand other issues not mentioned from the following description.

In order to achieve the above-mentioned purpose, one aspect of the present invention provides a polyimide film, which satisfies the following formula (1) in the dimensional change measurement based on a thermomechanical analyzer (TMA) after a heating process from 25°C to 400°C and a cooling process from 400°C to 25°C.

Formula (1) TD direction dimension measurement value (cooling, 50℃) - TD direction dimension measurement value (heating, 50℃) <0μm

In the above formula 1, the TD direction dimension measurement value (cooling, 50°C) is the TD direction dimension measurement value measured at 50°C during the cooling process.

The TD direction dimension measurement value (heating, 50°C) is the TD direction dimension measurement value measured at 50°C at the beginning of the heating process.

Another aspect of the present invention provides a method for manufacturing a polyimide film, as a method for manufacturing the aforementioned polyimide film, comprising: a process of providing a polyimide solution obtained from a dianhydride component and a diamine component; a process of casting and coating the aforementioned polyimide solution on a support and heating to manufacture a self-supporting film of the polyimide solution; and a process of imidizing and stretching the aforementioned self-supporting film to manufacture a polyimide film.

Another aspect of the present invention provides a flexible metal foil laminate comprising the aforementioned polyimide film and a conductive metal foil.

Another aspect of the present invention provides an electronic component including the aforementioned flexible metal foil laminate.

The present invention provides a polyimide film having a specific dimensional variation range, thereby providing a polyimide film having excellent flatness even after metal foil lamination.

This polyimide film can be applied to various fields requiring a polyimide film with excellent flatness, for example, it can be applied to a flexible metal-clad laminate produced by a metallization method or an electronic component including such a flexible metal-clad laminate.

Figure 1 is a graph showing the results of the dimensional change measurement based on a thermomechanical analyzer (TMA) of the films of Examples 1 and 2 of the present invention after a heating process from 25°C to 400°C and a cooling process from 400°C to 25°C.

Figure 2 is a graph showing the results of the dimensional change measurement based on a thermomechanical analyzer (TMA) of the films of Comparative Examples 1 to 3 of the present invention after a heating process from 25°C to 400°C and a cooling process from 400°C to 25°C.

The terms or words used in this specification and the scope of the patent application shall not be interpreted in a limited manner based on the usual meaning or dictionary meaning, but shall be interpreted only as the meaning and concept that conforms to the technical idea of the invention based on the principle that "the inventor may appropriately define the concept of the term in order to explain his own invention in the best way".

Therefore, the configuration of the embodiments described in this specification is only one of the best embodiments of the present invention, and does not all represent the technical ideas of the present invention. Therefore, it should be understood that there are various equivalents and equivalents that can be substituted at the time of the present invention. Variations.

As long as the context does not clearly indicate otherwise, singular expressions used in this specification include plural expressions. In this specification, terms such as "including", "having" or "having" are intended to specify the existence of implemented features, numbers, steps, constituent elements or their combinations, and should be understood as not excluding the possibility of the existence or addition of one or more other features, numbers, steps, constituent elements or their combinations in advance.

In this specification, "dianhydride" is meant to include its precursors or derivatives, which may not technically be dianhydrides but still react with diamines to form polyamides, which can be converted again to polyimides.

In this specification, "diamine" is meant to include precursors or derivatives thereof, which may not technically be diamines but still react with dianhydrides to form polyamides, which can be converted again to polyimides.

In this specification, when the amount, concentration or other value or parameter is given by listing a range, a preferred range or a preferred upper limit and a preferred lower limit, it should be understood that all ranges formed by any pair of any range upper limit or preferred value and any range lower limit or preferred value are specifically disclosed, regardless of whether the range is disclosed separately.

When a range of numerical values is mentioned in this specification, unless otherwise described, the range is meant to include its endpoints and all integers and fractions within the range. This means that the scope of the present invention is not limited to the specific values mentioned when defining the range.

According to an embodiment of the present invention, the polyimide film satisfies the following formula (1) in the dimensional change measurement based on a thermomechanical analyzer (TMA) after a heating process from 25°C to 400°C and a cooling process from 400°C to 25°C.

Formula (1) TD direction (width direction of the film, perpendicular to the MD direction) dimension measurement value (cooling, 50°C) - TD direction dimension measurement value (heating, 50°C) < 0μm

In the above formula 1, the TD direction dimension measurement value (cooling, 50°C) is the TD direction dimension measurement value measured at 50°C during the cooling process, and the TD direction dimension measurement value (heating, 50°C) is the TD direction dimension measurement value measured at 50°C at the beginning of the heating process.

That is, the polyimide film of the present invention is as shown in the above formula (1), and the difference between the TD direction dimension measurement value (cooling, 50°C) and the TD direction dimension measurement value (heating, 50°C) is a negative number.

This negative value is calculated because the polyimide film shrinks along the TD direction during the cooling process after heating.

Preferably, the value calculated according to the aforementioned formula (1) of the polyimide film of the present invention can be less than -5μm, more preferably, the value according to the aforementioned formula (1) can be less than -10μm, and most preferably, the value according to the aforementioned formula (1) can be less than -20μm.

The polyimide film with a negative value calculated according to the above formula (1) still maintains the flatness of the polyimide film after metal foil is layered by coating, sputtering or deposition, and almost no wrinkles occur.

When a polyimide film having a value of 0 or more calculated according to the above formula (1) is layered with a metal foil by coating, sputtering or deposition, the flatness of the polyimide film is reduced and wrinkles are frequently generated.

This calculated value above 0 is because the polyimide film expands along the TD direction during the cooling process after heating.

Among them, the aforementioned dimensional change measurement using a thermomechanical analyzer (TMA) was performed under the following conditions.

Measurement mode: tensile mode, load 5g, sample length: 15mm, sample width: 4mm, heating start temperature: 25℃, heating end temperature: 400℃ (no holding time at 400℃), cooling end temperature: 25℃, heating and cooling speed: 10℃/min, measurement atmosphere: nitrogen.

The thermal expansion coefficient (CTE) of the polyimide film of the present invention in the MD direction (continuous film-making direction; the length direction of the film, perpendicular to the TD direction) can be 2~6.5ppm/℃, and the thermal expansion coefficient in the TD direction can be 1~6ppm/℃.

In addition, the difference between the thermal expansion coefficient in the MD direction and the thermal expansion coefficient in the TD direction may be greater than 0 and less than 2.5 ppm/°C.

In addition, the elastic modulus of the aforementioned polyimide film can be greater than 5 GPa and less than 11 GPa, and the glass transition temperature can be greater than 360°C and less than 400°C.

In another aspect, the polyimide film of the present invention can be selected from pyromellitic anhydride (PMDA), oxydiphthalic anhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic anhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic anhydride (a-BPDA), 3,3,4,4-diphenylsulfonate tetracarboxylic anhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimellitic acid monoester anhydride ), p-biphenyl bis(trimellitic acid monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenyl One or more dianhydride components selected from the group consisting of p-phenylenediamine (PPD), m-phenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminobenzidine, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, and 4,4'-(2,2-hexafluoroisopropyl)diphthalic acid dianhydride; Toluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 4,4'-diaminodiphenyl ether (ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl Aminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diamine diphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone. 4'-Dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3 ,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis( (3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-bis(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenyl sulfide)benzene, 1,3-bis(4-aminophenyl sulfide)benzene, 1,4-bis(4-aminophenyl sulfide)benzene, 1, 3-Bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenyl) Biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-( 4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, bis[3-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane 、2,2-bis[3-(3-aminophenoxy)phenyl]propane、2,2-bis[3-(4-aminophenoxy)phenyl]propane、2,2-bis[4-(3-aminophenoxy)phenyl]propane、2,2-bis[4-(4-aminophenoxy)phenyl]propane(BAPP)、2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane、2 ,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane are subjected to an imidization reaction of one or more diamine components.

Preferably, the polyimide film can be obtained by subjecting a polyimide solution containing a dianhydride component and a diamine component to an imidization reaction, wherein the dianhydride component includes at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and pyromellitic dianhydride (PMDA), and the diamine component includes at least one of p-phenylenediamine (PPD) and 4,4'-diaminodiphenyl ether (ODA).

In addition, based on the total content of the aforementioned dianhydride component of 100 mol%, the content of the aforementioned biphenyltetracarboxylic dianhydride is 40 mol% or more and 60 mol% or less, the content of the aforementioned pyromellitic dianhydride is 40 mol% or more and 60 mol% or less, based on the total content of the aforementioned diamine component of 100 mol%, the content of the aforementioned p-phenylenediamine is 80 mol% or more and 90 mol% or less, and the content of the aforementioned 4,4'-diaminodiphenyl ether is 10 mol% or more and 20 mol% or less.

In the present invention, the production of polyamide acid can be carried out by the following methods, for example: (1) method, all diamine components are added to a solvent, and then the dianhydride component is added so that the diamine component and the dianhydride component are substantially equimolar and polymerized; (2) method, all dianhydride components are added to a solvent, and then the diamine component is added so that the dianhydride component and the dianhydride component are substantially equimolar and polymerized; (3) method, after adding a part of the diamine component to the solvent, a part of the dianhydride component is mixed at a ratio of about 95 to 105 mol% relative to the reaction component, and then the remaining diamine component is added, and then the remaining dianhydride component is added so that the diamine component and the dianhydride component are substantially equimolar and polymerized; (4) method, after adding the dianhydride component to the solvent, a part of the diamine compound component is mixed at a ratio of 95 to 105 mol% relative to the reaction component. After that, the other dianhydride component is added, and then the remaining diamine component is added, so that the diamine component and the dianhydride component are substantially equimolar and then polymerized; (5) method, in a solvent, a part of the diamine component and a part of the dianhydride component are reacted to make either one excessive to form a first composition, and in another solvent, a part of the diamine component and a part of the dianhydride component are reacted to make either one excessive to form a second composition, and then the first and second compositions are mixed to complete the polymerization. At this time, when the diamine component is excessive in the formation of the first composition, the dianhydride component is excessive in the second composition, and when the dianhydride component is excessive in the first composition, the diamine component is excessive in the second composition, and the first and second compositions are mixed to make the total diamine component and dianhydride component used in the reaction substantially equimolar and then polymerized.

In a specific example, the method for manufacturing a polyimide film according to the present invention may include: a process of providing a polyimide solution obtained from a dianhydride component and a diamine component; a process of casting and coating the polyimide solution on a support and heating to manufacture a self-supporting film of the polyimide solution; and a process of imidizing and stretching the self-supporting film to manufacture a polyimide film.

The aforementioned stretching is biaxial stretching, and the tension is applied in such a way that the stretching ratio in the MD direction is the same as that in the TD direction.

This stretching ratio can be confirmed by the balance between the MD direction and the TD direction of the polyimide film using the aforementioned TMA measurement.

That is, the balance between the MD direction and the TD direction of the polyimide film obtained by stretching is expressed as follows: the difference between the thermal expansion coefficient in the MD direction and the thermal expansion coefficient in the TD direction is greater than 0 and less than 2.5 ppm/°C.

In the present invention, the polymerization method of the polyamine acid as described above can be defined as a random polymerization method, and the polyimide film produced by the polyamine acid of the present invention produced by the above-mentioned process can be preferably used in maximizing the flatness improvement effect of the present invention.

However, the aforementioned polymerization method has limitations in terms of exerting the various excellent properties of the polyimide chain derived from the dianhydride component because the length of the repeating unit in the polymer chain described above is relatively short. Therefore, the polymerization method of polyamide acid that can be preferably utilized in the present invention can be block polymerization.

On the other hand, the solvent used to synthesize polyamine is not particularly limited. Any solvent can be used as long as it can dissolve polyamine, but amide solvents are preferred.

Specifically, the aforementioned solvent may be an organic polar solvent, more specifically, an aprotic polar solvent, for example, one or more selected from the group consisting of N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylpyrrolidone (NMP), γ-butyrolactone (GBL), and diethylene glycol dimethyl ether (Diglyme), but is not limited thereto, and may be used alone or in combination of two or more as needed.

In one example, the aforementioned solvents are preferably N,N-dimethylformamide and N,N-dimethylacetamide.

In addition, fillers can also be added during the polyamide manufacturing process to improve various properties of the film, such as slip, thermal conductivity, corona resistance, and ring hardness. The added fillers are not particularly limited, and as preferred examples, they can be silicon dioxide, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, etc.

The particle size of the filler is not particularly limited and can be determined according to the film properties to be improved and the type of filler added. Generally speaking, the average particle size is 0.05μm to 100μm, preferably 0.1μm to 75μm, more preferably 0.1μm to 50μm, and particularly preferably 0.1μm to 25μm.

If the particle size is below this range, it is difficult to show the improvement effect. If it exceeds this range, there is a possibility that the surface is greatly damaged or the mechanical properties are greatly reduced.

In addition, there is no special limit on the amount of filler added, which can be determined according to the film properties to be improved or the filler particle size. Generally speaking, the amount of filler added is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight relative to 100 parts by weight of polyimide.

If the amount of filler added is lower than this range, it is difficult to show the improvement effect of the filler. If it exceeds this range, there is a possibility that the mechanical properties of the film will be greatly damaged. The method of adding the filler is not particularly limited, and any known method can be used.

In the manufacturing method of the present invention, the polyimide membrane can be manufactured according to the thermal imidization method and the chemical imidization method.

In addition, it can also be manufactured by a composite imidization method that combines thermal imidization and chemical imidization.

The so-called thermal imidization method mentioned above is a method that uses a heat source such as hot air or an infrared dryer to induce the imidization reaction without using a chemical catalyst.

The aforementioned thermal imidization method can heat-treat the aforementioned gel film at a variable temperature in the range of 100 to 600°C to achieve imidization of the amide groups in the gel film. Specifically, the heat treatment can be performed at 200 to 500°C, and more specifically, at 300 to 500°C to achieve imidization of the amide groups in the gel film.

However, during the process of forming the gel film, a portion of the polyamine (about 0.1 mol% to 10 mol%) will be imidized. For this purpose, the polyamine composition can be dried at a variable temperature ranging from 50°C to 200°C, which can also be included in the scope of the aforementioned thermal imidization method.

As for the chemical imidization method, a polyimide membrane can be produced using a dehydrating agent and an imidizing agent according to methods known in the industry.

As an example of the composite imidization method, a dehydrating agent and an imidizing agent are added to a polyamide solution, and then heated at 80 to 200°C, preferably 100 to 180°C. After partial curing and drying, the solution is heated at 200 to 400°C for 5 to 400 seconds to produce a polyimide film.

The present invention provides a flexible metal foil-clad laminate comprising the polyimide film as described above and a conductive metal foil.

The metal foil used is not particularly limited, but when the flexible metal foil laminate of the present invention is used for electronic equipment or electrical equipment, for example, it can be a metal foil including copper or copper alloy, stainless steel or its alloy, nickel or nickel alloy (including 42 alloy), aluminum or aluminum alloy.

Among ordinary flexible metal foil laminated plates, copper foils called rolled copper foils and electrolytic copper foils are widely used and can also be preferably used in the present invention. In addition, a rust-proof layer, a heat-resistant layer or an adhesive layer can also be coated on the surface of these metal foils.

In the present invention, the thickness of the aforementioned metal foil is not particularly limited, and it can be any thickness that can fully exert its function according to its use.

The flexible metal foil laminated plate according to the present invention can be obtained by laminating, coating, sputtering or depositing metal foil on at least one side of the aforementioned polyimide film.

In addition, the aforementioned flexible metal foil laminate can be used as a two-layer FCCL, especially for portable phones, display devices (LCD, PDP, OLED, etc.), etc., and can be used for FPCB and COF.

The electronic components including the aforementioned flexible metal foil laminate may be, for example, communication circuits for portable terminals, communication circuits for computers, or communication circuits for aerospace, but are not limited thereto.

The following is a more detailed description of the functions and effects of the invention through specific manufacturing examples and implementation examples. However, such manufacturing examples and implementation examples are only proposed as examples of the invention, and the scope of the invention is not limited thereby.

Manufacturing example: Manufacturing of polyimide film

The polyimide film of the present invention can be produced by the following common method known in the industry. First, the aforementioned dianhydride and diamine components are reacted in an organic solvent to obtain a polyimide solution.

At this time, the solvent is generally an amide solvent, and an aprotic polar solvent can be used, such as N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone or a combination thereof.

The aforementioned dianhydride and diamine components can be added in the form of powder, agglomerate or solution. After adding them in the form of powder at the initial stage of the reaction and reacting, it is preferred to add them in the form of solution in order to adjust the polymerization viscosity.

The obtained polyamine solution can be mixed with an imidization catalyst and a dehydrating agent and coated on a support.

Examples of catalysts include tertiary amines (e.g., isoquinoline, β-methylpyridine, pyridine, etc.), and examples of dehydrating agents include acid anhydrides, but are not limited to these. In addition, the supporting bodies used above may include, for example, glass plates, aluminum foils, annular stainless steel belts, or stainless steel barrels, but are not limited to these.

The film coated on the aforementioned support body is gelled on the support body by dry air and heat treatment.

The gelled film is separated from the support and heat treated to achieve drying and acylation.

The film that has completed the above heat treatment is heat treated under a given tension to remove the residual stress inside the film that occurred during the film making process.

Specifically, 500 ml of DMF was added while nitrogen was injected into a reactor equipped with a stirrer, a nitrogen injection pipe, and a discharge pipe. After the reactor temperature was set to 30°C, biphenyltetracarboxylic dianhydride (50 mol%), pyromellitic dianhydride (50 mol%), p-phenylenediamine (87 mol%), and 4,4'-diaminodiphenyl ether (13 mol%) were added in an adjusted ratio and a predetermined order and completely dissolved. Then, the temperature of the reactor was raised to 40°C and stirred for 120 minutes under a nitrogen atmosphere to produce polyamide with a primary reaction viscosity of 1500 cP.

The polyamine thus produced is stirred to achieve a final viscosity of 100,000~120,000 cP.

The catalyst and dehydrating agent contents were adjusted and added to the prepared final polyimide, and the polyimide membrane was manufactured using a coater.

Implementation examples and comparative examples

According to the above manufacturing example, as shown in Table 1 below, the stretching degree of the embodiment and the comparative example was adjusted to produce a polyimide film.

That is, when the stretching degree of Example 1 is regarded as 100%, the stretching degree of Example 2 is 120%, and the stretching degrees of Comparative Examples 1 to 3 are 150%, 140% and 70%, respectively.

The coefficient of thermal expansion (CTE), glass transition temperature, elastic modulus of the fabricated polyimide film and the flatness after metal foil lamination were measured.

In addition, after forming a metal layer on the manufactured polyimide film by sputtering, the flatness of the film after coating (the amount of wrinkles generated) was confirmed.

(1) Measuring dimensional changes

The dimensional changes based on thermomechanical analysis (TMA) were measured following a heating process from 25°C to 400°C and a cooling process from 400°C to 25°C.

(2)Measurement of thermal expansion coefficient

The coefficient of thermal expansion (CTE) was measured using a TA company thermomechanical analyzer Q400. The polyimide film was cut into pieces with a width of 4 mm and a length of 20 mm. A tension of 0.05 N was applied in a nitrogen atmosphere. The temperature was raised from room temperature to 300°C at a rate of 10°C/min and then cooled again at a rate of 10°C/min. The slope in the range of 100°C to 200°C was also measured.

(3) Measuring film flatness

By visual inspection, wrinkles along the MD direction of the manufactured polyimide film were confirmed.

(4) Measuring glass transition temperature

Glass transition temperature ( _Tg ) The loss modulus and storage modulus of each film were determined using DMA, and the inflection point in the tangent graph was measured as the glass transition temperature.

(5)Measure elastic modulus

The elastic modulus of the polyimide film was measured according to ASTM D882.

The dimensional change measurement results of Example 1 and Example 2 are shown in Figure 1 (a) and Figure 1 (b), respectively. In addition, the dimensional change measurement results of Comparative Examples 1 to 3 are shown in Figure 2 (a), Figure 2 (b), and Figure 2 (c), respectively.

As shown in FIG1 , the calculated values of Example 1 and Example 2 according to Formula (1) are equal to negative numbers. In addition, as shown in FIG2 , the calculated values of Comparative Examples 1 to 3 according to Formula (1) are equal to positive numbers.

The results of the flatness measurement of the film after coating show that compared with the polyimide films of Comparative Examples 1 to Comparative Examples 3, whose calculated values according to formula (1) are positive numbers, the polyimide films of Examples 1 and 2, whose calculated values according to formula (1) are negative numbers, have very excellent film flatness (no or almost no wrinkles are generated)

The embodiments of the polyimide film and the method for manufacturing the polyimide film of the present invention are only to enable the general skilled person in the technical field to which the present invention belongs to easily implement the preferred embodiments of the present invention, and are not limited to the aforementioned embodiments. Therefore, the scope of the patent application of the present invention is not limited thereby. Therefore, the true technical protection scope of the present invention should be determined according to the technical idea of the accompanying patent application scope. In addition, practitioners should understand that various substitutions, deformations and changes can be realized within the scope of the technical idea of the present invention, and the parts that can be easily changed by practitioners are also included in the scope of the patent application of the present invention. This is self-evident.

Claims (7)

A polyimide film, wherein the polyimide film satisfies the following formula (1) in the dimensional change measurement based on a thermomechanical analyzer after a heating process from 25°C to 400°C and then a cooling process from 400°C to 25°C: Formula (1) Transverse direction (TD) dimension measurement value (cooling, 50°C) - transverse direction (TD) dimension measurement value (heating, 50°C) < 0 μm In the above formula (1), the above transverse direction (TD) dimension measurement value (cooling, 50°C) is the transverse direction (TD) dimension measurement value measured at 50°C during the cooling process, The transverse direction (TD) dimension measurement value (heating, 50°C) is the transverse direction (TD) dimension measurement value measured at 50°C during the heating process, wherein the polyimide film is obtained by subjecting a polyimide solution containing a dianhydride component and a diamine component to imidization, wherein the dianhydride component contains 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and pyromellitic dianhydride (PMDA), and the diamine component contains p-phenylenediamine (PPD) and 4,4'-diaminodiphenyl ether (ODA), wherein ... Based on the total content of the anhydride components as 100 mol%, the content of the 3,3',4,4'-biphenyltetracarboxylic dianhydride is 40 mol% or more and 60 mol% or less, the content of the pyromellitic dianhydride is 40 mol% or more and 60 mol% or less, based on the total content of the diamine components as 100 mol%, the content of the p-phenylenediamine is 80 mol% or more and 90 mol% or less, the content of the 4,4'-diaminodiphenyl ether is 10 mol% or more and 20 mol% or less, wherein the machine direction (MD) of the polyimide film The thermal expansion coefficient is 2 to 6.5 ppm/°C, the thermal expansion coefficient in the transverse direction (TD) is 1 to 6 ppm/°C, wherein the difference between the thermal expansion coefficient in the machine direction (MD) and the thermal expansion coefficient in the transverse direction (TD) is greater than 0 and less than 2.5 ppm/°C, wherein the glass transition temperature of the polyimide film is greater than 360°C and less than 400°C, and wherein the polyimide film is made by stretching at the same stretching ratio in the machine direction (MD) and the transverse direction (TD). The polyimide film as described in claim 1, wherein the elastic modulus of the polyimide film is greater than 5 GPa and less than 11 GPa. The polyimide film as described in claim 1, wherein the polyimide film is obtained by subjecting the polyimide solution further comprising the following to an imidization reaction: free oxydiphthalic anhydride (ODPA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,3,4,4-diphenylsulfonate tetracarboxylic dianhydride (DSDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) and 2,2-bis[(3,4-dicarboxylic One or more dianhydride components selected from the group consisting of 2,2'-dimethylbenzidine, 3,5-diaminobenzoic acid (DABA), 3,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP). A method for producing a polyimide film, which is a method for producing a polyimide film as described in any one of claims 1 to 3, the aforementioned production method comprising the following steps: a process of providing a polyimide solution obtained from a dianhydride component and a diamine component; a process of casting and coating the aforementioned polyimide solution on a support and heating to produce a self-supporting film of the aforementioned polyimide solution; and a process of imidizing and stretching the aforementioned self-supporting film to produce a polyimide film. A flexible metal foil laminate comprising a polyimide film as described in any one of claims 1 to 3; and a conductive metal foil. A flexible metal foil laminate as described in claim 5, wherein the conductive metal foil is formed by coating, sputtering or deposition. An electronic component comprising a flexible metal foil laminate as described in claim 6.

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